Possessives and Attributives

Q. What is the proper way to cite information found in a footnote? Take, for example, the following footnote: “2. It is however to be observed that in the given proposition there is a certain ambiguity.” I wish to cite this in the footnote of my own paper. In some works, I’ve seen what I suspect to be the same thing accomplished by appending the page number with “f,” e.g., 67f.

A. That f actually stands for “and the following page.” The letter n is used to stand for a note (whether endnote or footnote): 67n2.